Pectoralis major muscle

The pectoralis major muscle (Latin for " greater pectoral muscle " or " pectoralis major ") is a skeletal muscle and covers the entire front rib area. On the arm overlap the fibers of the pectoralis: The fibers that come from far down, put on the upper arm further up than the fibers that come from the clavicle. This creates a sheet which forms the front boundary of the armpit. The pectoralis major covers the small chest muscle ( pectoralis minor). On the outside is to him the Brustfaszie which separates him from the superficial layer of the chest wall.

The large chest muscle consists of three parts:

• Clavicular ( collarbone part )
• Sternocostal ( sternum -rib part )
• Pars abdominalis ( abdominal part )

Function

The pectoralis major muscle pulls the arm towards the body ( adduction), turning it inward ( medial) and pulls it forward ( anteversion ). He also belongs to the respiratory muscles. However, depending on the position of the upper arm of the pectoralis changed its function. In 90 degrees forward flexion contraction leads to an abduction of the arm.

Varieties

In the first place there may be adhesions with the latissimus dorsi or the deltoid muscle, then a clear visual separation of these muscles is hardly possible. These adhesions are not uncommon; they come at about 7 % before all people.

The pectoralis major muscle can be missing completely on one side. This known as Poland syndrome defect occurs at one of 20,000 children, with boys four times as often as girls. Until now, the cause is not exactly known, but it is assumed that the cause is not due to a genetic defect. Most adhesions also occur on the same side hand.